I thought Yoshi wants healer to focus on healing only..

[JunseiKei]

Would you be happy playing a DPS class where all you had was your one single "use weapon" button that you hit over and over again? Just one button and that's the entirety of your class? Do you feel that would be engaging, or fun in any way? Do you think people would want to play a class like that?

This is a hyperbole. If the DPS had to do other things outside of that one button, like healing, since healers have been regulated to "green DPS," then yes, because healers do this. They've done this as DoTs were only pressed every so often as it were and you spammed Broil or Stone 95% of the rest of the time. Astrologian has been the only class that has more consistent actions needed because of the card system that isn't a DPS spell. If this is something you truly hate, then that class is not for you, so take up another.

Better gear, the healer getting better at their role, people getting hit by less avoidable things, all this leads to less healing. When less healing is required, some of us like to actually continue to contribute to the fight in spite of this, hence DPSing.

Gear does not make you survive more. Well, it does, but it's not needed. You have all of the tools available to survive, or these world firsts wouldn't be nearly as fast as they are. If you're dying solely to damage, people aren't using mitigation correctly. Most people don't actually blindly prog, so aside from actually learning the mechanics (getting hit less by avoidable damage, etc), there shouldn't be a case of getting better at your role. You can map out the encounter for when to use raid buffs, mitigation, heals, etc., without ever stepping foot into it.

Unfortunately, it feels like SE feels that our "reward" for doing well at content should be to then just spam a single button and occasionally one other button. Hooray.

Yes, you've made it quite clear that you enjoy button bloat.